NZXT C1500 Platinum ATX 3.1 Power Supply Review

PSU technology continues to move forward, and while it's always been the most important component in any system build, I feel that's even more true today, with the higher power demands of flagship processors and graphics cards demanding higher wattage power supplies than ever before. Of course, more power means more running costs, so with higher wattages especially, efficiency becomes even more important. However, at 1500W and with 80 Plus Platinum/Cybernetics Titanium efficiency, the latest NZXT C1500 ATX 3.1 power supply is firmly ticking both of those boxes. Meeting the latest ATX 3.1 and PCIe 5.1 standards, and coming equipped with a pair of 12VHPWR connectors, this power supply is extremely capable. For driving multiple graphics cards, while also providing future-proofing for upcoming hardware, it's going to be well suited to high-end workstations, extreme gaming PCs and meet the demands of overclocking enthusiasts with ease. Or at least, it should, but we'll be putting all of that to the test shortly! NZXT C1500 Features Designed with ATX 3.1 and PCIe 5.1 compliance to power current and future generations of high-performance GPUs and CPUs. Includes two 16-pin 12V-2x6 PCIe 5.1 cables, each capable of delivering over 600 watts to power-hungry GPUs. Digital power enables precise voltage regulation, resulting in higher efficiency and lower ripple noise. Exceeding 80 Plus Platinum standards and boasting a Cybenetics Titanium efficiency rating, the 94% efficiency lowers power usage and ensures quieter, cooler operation. Constructed using high-quality 105°C Japanese capacitors for excellent reliability and long-lasting performance. Fully modular design simplifies cable management, allowing for the connection of only necessary cables. Compact 180mm form factor optimizes valuable case space while promoting improved airflow. Packaging & Accessories The box is classic NZXT, with a white and purple theme that see see throughout their entire range of products. There's a large and clear photo on the front of the box, showing the overall design, as well as the range of power connectors on the back. The box clearly details all of the key features such as the wattage, digital power design, efficiency, and key specifications of the fan and included cables. In the box, you'll find a vibrant NZXT-purple bag for storing all of the PSU cables, and since it's unlikely you'll be using all the cables in a single build (well, maybe YOU will!), it's nice to have a good quality protective bag to store them. All of the cables are black with black connectors, and a glossy and durable black sleeving. None of the cables come with a flag design, they're all a bit rounded, but this is more common with such high wattage PSUs, which typically use thicker cables to deal with the higher power and thermal loads. A Closer Look NZXT has opted to give this PSU a clean and modern aesthetic, which isn't surprising, since they've deployed the same design philosophy on their latest cases, coolers, motherboards, and even their peripherals. For now, this PSU is only available in black, but given other models in the series were eventually made available in white, I wouldn't be surprised to see a white model follow along in the near future. The PSU features a larger 140mm fan for big airflow with lower noise, and a flush mounted aluminium top cover to keep things looking clean and tidy. Around the back of the PSU, there's plenty of ventilation for heat exhaust, with a master power switch, as well as a hybrid fan switch to toggle active (always on) fan mode, or the passive mode that will use zero RPM fan mode when the PSU is under lower loads and temperatures. You'll notice the square cable connector (C19) too, which are more common on extreme wattage PSUs, as they come with a higher rated power cable than a standard PSU. Branding is kept very clean, a subtle black "NZXT C1500" logo on each side, and even the specifications sticker on the back is pretty unobtrusive. Onto the business end, you'll find a plethora of connectors, with a split 24-pin connector, nine CPU & PCIe connectors, four peripherals & SATA connectors, and most importantly, a pair of 12VHPWR connectors for current and next gen high power devices such as graphics cards. A Closer Look - Interior This power supply uses the Sunon MagLev fan, technically known as the MFE0251VX-1Q010-S99. This 140mm DC12 fan is one of the most high-end fans we've seen in a PSU, with a 100,000 hours claimed operational life span, improved dust resistance, and lower noise levels compared to more traditional FDB style fans. However, it is rated for up to 2500RPM, which is seriously fast, but on a long-hot, hard-working day, it's good to know the PSU can push hard to cool its self if needed. The interior of the PSU is very clean, despite having so much hardware crammed into it. 1500W is a lot of power, so while I've never seen three main bulk capacitors in a single PSU, I can't say I'm surprised to see them here either. All of the main capacitors are premium quality 150c-rated Nippon units which are rated for 420V and 820uF each. Honestly, I have a feeling the peak output of this PSU will far exceed the rated 1500W when we get to testing! The design is very well laid out to promote good airflow around all components, with a series of daughter boards freeing up horizontal space on the PCB. It's a digitally controlled unit too, which helps it reach its impressive power levels and efficiency ratings. Towards the back, we can the 3.3v and 5v coils. The AC-line in is very clean, with a board here providing a more robust mounting point for the C19 socket, but also more shielding and filtering, which will reduce any unwanted input noise. There's a robust looking heatsink running down the middle of the PCB, which also seems to act like a buffer between the capacitors and the two large transformers on the side of the unit. Overall, there are no unwanted trailing cables, there's shielding and coverings on all important hardware, and the choice of components looks to be excellent throughout. So with that in mind, let's see what this PSU can really do! Methodology & Testing At eTeknix we take the power supply testing procedure very seriously and have invested a lot of resources into acquiring the appropriate testing equipment. For all power supply reviews, we test the power supplies with dedicated power supply testing equipment. This means we can get the most accurate results from our testing as opposed to using software benchmarks (such as OCCT) or multi-meter readouts which are broadly inaccurate. Testing Hardware Sunmoon SM-8800 Active Load Tester Stingray DS1M12 USB Oscilloscope Voltcraft DT-10L laser tachometer What the eTeknix Test Procedure Involves Testing each power supply at 20/40/60/80/100% load (with load balanced across all rails) and measuring PFC (power factor correction), efficiency (actual power divided by power "pulled at the wall") which also uses a 50% load test, and voltage regulation (deviance from expected voltages of 3.3/5/12 on the main rails). Measuring ripple with an oscilloscope at 20/40/60/80/100% load. Transient loads taken with an oscilloscope are taken from 0% to 100% on the 12v raid, 3.3v rail, and then both combined. Measuring fan speed after a stabilisation period of five minutes at each loading scenario using the Voltcraft DT-10L laser tachometer and a reflective strip on the fan. Testing each power supply's OPP (Over Power Protection) mechanism and seeing how many watts each power supply can deliver before shutting down. Any deviation from this will be explained per review as appropriate on the respective testing pages, but this methodology page will remain unchanged. Other Things to Consider We recognise that a single 12-volt cable can provide only 6 Amps before overheating (which corrupts voltage regulation and efficiency) so we used an adequate number of cables for each power supply to ensure there is no efficiency loss from poor cable selection. If there is more than one 12VHPWR on a PSU, all will be used to test their combined loads. We use the same time scale and horizontal millivolt scale on our oscilloscope for all ripple tests, that is a 20ms T/DIV (horizontal) and a 0.02 V/DIV (vertical) meaning the scale is from -80mV to +80mV, ATX spec dictates that the 12v rail must fall within 150mv of ripple and the 3.3/5 within 50mv so that scale allows us to include both 150 and 50mV peaks. (Some older PSU reviews use different scales which were later ditched as the visual representation they give is inadequate, in these reviews written measurements are provided only). Deviance is the terminology used to represent the way voltages diverge from the expected values Voltage Regulation To test voltage regulation we load the power supply to five different load scenarios that give an equal spread of load across every single rail. So that means 20% on all rails, 40% on all rails and so on. We then calculate the average deviation of each rail from its expected voltage. Ideally, anything of +/- 2% regulation is seen as a very good result. Power Efficiency Power efficiency is measured by calculating the supplied wattage divided by the wattage drawn at the wall/plug, multiplied by 100 to give a percentage. We then compare that to the particular 80 Plus certification the company claims to see if it meets that. You can see the 80 Plus certifications below, we always test power supplies at 230v. Transient Loads Power Factor Correction Power Factor Correction is the ratio of the real power flowing to the load, to the apparent power in the circuit. PFC aims to make the load circuitry that is power factor corrected appear purely resistive (apparent power equal to real power). In this case, the voltage and current are in phase and the reactive power consumption is zero. The closer the number to one the better as this allows the most efficient delivery of electrical power (Source - Wikipedia). Ripple An oscilloscope can easily measure noise and Ripple. These show how much voltage fluctuation there is on a particular rail. We tested the rail stability of the 3.3-volt, 5-volt and 12-volt rails using an identical time and millivolt scale for all graphs. millivolt ripple is measured by the peak-to-peak size of the voltage curve. The latest ATX 12-volt version 2.3 specifications state that ripple from peak to peak must be no higher than 50 millivolts for the 3.3-volt and 5-volt rails, while the 12-volt rail is allowed up to 120 millivolts peak to peak to stay within specifications. Millivolt figures are stated to the closest increment of 5 given their variability. OPP Power supplies are often quoted as having various protection mechanisms and the most important of these is Over Power Protection. In our testing, we crank up the power draw until the power supply either shuts down (meaning the OPP mechanism is present and working) or blows up (meaning it is either not present or not working). We then note the maximum power consumption before the power supply shut down, or before it blew up. Fan Speed When testing in a power supply laboratory it is difficult to take fan noise readings as the noise from the Sunmoon test equipment and air conditioning corrupts everything. The next best thing in our circumstances was reading off the fan speed with a tachometer to get an idea of the noise. The ambient temperature during testing is held constant at 22 degrees, with 1 degree of variation. Each power supply had a consistent period of 5 minutes to stabilise between each load scenario. In my experience, the following general relationships apply between noise levels and fan speeds, though it can vary greatly between the type of fan used. Below 800 RPM - Inaudible/Silent 800 to 1000 RPM - Barely audible 1000 - 1200 RPM - Audible but still quiet 1200 - 1400 RPM - Moderately noisy 1400 - 1800 RPM - Noisy 1800 - 2000 RPM or above - Intolerable Internal Components This is just an example of what you can expect to see on a PSU interior. Efficiency Digital PSU platforms are fantastic when it comes to efficiency, which means it's no surprise to see it firmly in the low to mid 90% throughout all of our testing, with a very consistent PFC meaning less power is wasted and overall less heat is generated too. PFC (Power Factor Correction) Voltage Regulation Voltage regular is very tight, with 3.3v sitting a bit low, but given every 3.3v device typically draws from the motherboard these days, fed by the 12v line, it's really not a big deal. Overall though, all the important voltages for a modern system are within 1%, which is incredible. Ripple Ripple is incredibly low, not that I was expecting anything else though, but these are certainly some of the best results we've seen from any PSU ever. 3.3V 5V 12V Over Power Protection and Max Wattage 1500W is a lot of power, but honestly, this PSU is seriously over built. Three main bulk capacitors is a lot, and they're good quality units, so it's no surprise I was able to pull a little over 2000W before the OPP kicked in! Transient Loads These results measure the power supply from 0% load to 100% load on various rails to simulate a power spike from your system. Typically, we would like to see as small a spike as possible relative to the requested voltage. With modern GPUs being notorious for power spikes, this is becoming more relevant in modern PSU design. Transients are clean and fast, no over or under shoot, but again, given the quality of the PSU, this is hardly surprising. 0-100% 3V 0-100% +5VSB 0-100% 12V Cross-Loads We want to see no more than a +/- 3% deviance in any crossload test, but the C1500 was well within half as much, so again, absolutely no issues here. Fan Speed The fan curve is adjustable via the hybrid switch on the unit. With hybrid enabled, the fan doesn't kick in till about 50% load, which is impressive, as that's around 850W of silent power. Of course, it'll likely start up on a hot day as temperature can trigger the fan too. The fan didn't reach is maximum speed even at 100% power, but that's a good sign, as the PSU never really got more than a little warm to the touch, so the fan still have some extra power should it be needed on a very hot day of gaming. How Much Does it Cost? At £299.99, it's fair to say that this power supply is pretty expensive, but when it comes to requiring high wattage, high build quality and excellent efficiency, you certainly get what you pay for. However, looking through rival power supplies from the likes of Seasonic, Silverstone, Enermax, Corsair and a few others, they've all got something broadly similar for around the same price, but more often than not, NZXT's unit is a little bit cheaper, making it extremely competitive. Overview Finding a quality power supply is easier today than it's ever been, with all the big name brands having some really great units on the market, and a good quality unit is more affordable than ever too. Of course, this latest unit from NZXT is a fair bit above the entry level of good quality PSUs, and that much is reflected in the price tag. Of course, dropping £299 on a PSU isn't something everyone is eager to do, but when you see the quality and performance on offer, it doesn't seem unreasonable. If you're pushing the latest graphics cards, such as the RTX 4090, and want to be ready for the next-generation from AMD or Nvidia, then I'm certain that the C1500 will do the job. Even more so, if you're running two graphics cards for your AI, video editing or graphics workstation, then a PSU of this quality will more than keep up with the job. Of course, it also gives you the performance needed to also power a high-end AMD or Intel processor and other hardware too. With high power draw, efficiency becomes even more important. While I hear from a lot of our gamer readers that they don't care too much about efficiency, I feel that they should. Running costs can be higher than a lot of people realise, and at 1000W+ it becomes noticeable. Which such high efficiency, this PSU is going to be much cheaper and greener to run on a daily basis. However, efficiency goes another way, less power required to create the desired output also means less power is wasted, meaning less heat is generated, meaning the PSU runs cooler and quieter than its less efficient rivals. Should I Buy One? If you need a feature rich power supply with a plethora of available connections for lots of storage, add-on devices, powerful hungry motherboards/CPU multiple high-end graphics cards and anything else, the C1500 from NZXT has everything you could ask for in a premium quality power supply. Big power, excellent efficiency, low noise, and impeccable build quality make this one of the absolute best all-round PSUs we've tested in recent years.